Alcaparrosaite is a rare sulfate mineral that forms as a secondary mineral in oxidized iron-rich mine environments. It is characterized by its distinctive yellow tabular crystal habit and is primarily sought after by advanced collectors of rare sulfate species.
Is this alcaparrosaite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch alcaparrosaite with a known reference. Alcaparrosaite sits at Mohs ~4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: pale yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals.
Often confused with
Alcaparrosaite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Alcaparrosaite is noticeably harder (Mohs ~4 vs. 2.5).
How to tell apart: Alcaparrosaite is noticeably harder (Mohs ~4 vs. 2.5-3); streak differs, so Alcaparrosaite leaves white, Copiapite leaves pale yellow; luster reads vitreous on Alcaparrosaite and pearly on {010} on Copiapite.
Often found alongside alcaparrosaite
Minerals reported to co-occur with alcaparrosaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₃TiFe³⁺(SO₄)₄O·2H₂O
- Mohs hardness
- ~4
- Density
- 2.80 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- Formed by the oxidation of pyritic masses under increasingly arid conditions, likely at a relatively early stage
Where rockhounds find alcaparrosaite
Classic worldwide localities
- Alcaparrosa mine, Cerritos Bayos, El Loa Province, Antofagasta, Chile
Field-hunting tip
Where it forms: Formed by the oxidation of pyritic masses under increasingly arid conditions, likely at a relatively early stage. If you start seeing intergrown with coquimbite, associated with ferrinatrite, krausite in float, you are in the right ground. Typical habit: tabular crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify alcaparrosaite?+
Where is alcaparrosaite found?+
What rocks look like alcaparrosaite?+
What minerals are found with alcaparrosaite?+
What kind of rock does alcaparrosaite form in?+
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Find alcaparrosaite on the map
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